1. Field of the Invention
The present invention relates to a vehicle control system.
2. Description of Related Art
A vehicle control system, which determines a shape of a road that is ahead of a vehicle and controls a speed of the vehicle, is conventionally proposed (e.g., JP3432881B2). According to the vehicle control system in JP3432881 B2, when the vehicle is decelerated with a predetermined deceleration from a vehicle speed V0, a distance (a foreseen distance), which is traveled until the vehicle stops within a predetermined time t2, is determined. A tentative vehicle position is set at a position ahead of the vehicle with the foreseen distance therebetween. A second reference node is set at the tentative vehicle position, and a third reference node is set at a position that is ahead of the second reference node with a distance A (i.e., the vehicle speed V0×a predetermined time t1) therebetween. In addition, a possible traveling vehicle speed, which is used in order that the vehicle travels between the second and third reference node with a reference lateral acceleration or lower, is obtained. When existence of a curve ahead of the vehicle is determined, and the vehicle speed V0 is larger than the possible traveling vehicle speed, the vehicle is automatically decelerated by a vehicle speed control means such that it travels safely along the curve.
However, when the vehicle speed V0 is larger than the possible traveling vehicle speed, the vehicle speed control means in the above vehicle control system does not set a target vehicle speed to automatically decelerate the vehicle such that the vehicle travels with the target vehicle speed. Therefore, there is a possibility that the vehicle is unduly decelerated by the automatic deceleration.
Furthermore, the above vehicle speed control means does not automatically accelerate the vehicle when the vehicle speed V0 is smaller than the possible traveling vehicle speed. Hence, the vehicle speed control means cannot assist a driver of the vehicle with his/her drive operation of the vehicle in a comprehensive manner when the vehicle travels along the curve.